Best ways to insulate a modified bitumen roof?

I've actually seen soffit and ridge vents combined on a bitumen roof once - worked pretty well from what I could tell. It was a low-slope setup, and the homeowner had issues with moisture buildup before. After adding soffit vents to get that airflow moving upward, things improved noticeably. But I'm curious if anyone's run into condensation problems with this combo in colder climates... seems like it could be tricky balancing insulation and ventilation when temps really drop.

I've seen similar setups around here (Midwest winters get pretty brutal), and condensation can definitely be an issue if insulation isn't spot-on. Wonder if using rigid foam insulation above the deck would help keep the dew point outside the structure...?

- Rigid foam above deck can def help - I inspected a place last winter with similar issues.
- They'd added rigid insulation externally, and condensation was noticeably reduced.
- Still curious though...wonder if ventilation adjustments would've been enough without the extra cost?

I've seen ventilation tweaks help in some cases, but with modified bitumen roofs, isn't the limited airflow a challenge? Wonder if anyone's tried combining minimal rigid foam with targeted venting adjustments...might strike a good balance without breaking the bank.

- Minimal rigid foam could help, but you'd need to be careful about condensation risks.
- Targeted venting adjustments make sense, though airflow is still limited with modified bitumen.
- Wonder if anyone's had success using breathable underlayments or vapor diffusion strategies instead?
- Seen mixed results myself - sometimes minor tweaks surprisingly effective, other times not so much...